Zero-configuration networking (zeroconf) typically refers to a set of techniques that automatically creates a usable Internet Protocol (IP) network without manual operator intervention or special configuration servers. Zeroconf protocols can enable service discovery, address assignment, and name resolution for desktop computers, mobile devices, and network devices. Different vendors often devises out their own approaches to achieve zero-configuration networking based on various public drafts and/or standards. Most standards use multicast-based link-local multicast addresses as a part of the solution, for example, multicast Domain Name System (mDNS) as defined in IETF RFC 6762, Link-local Multicast Name Resolution (LLMNR) as defined in IETF RFC 4795, etc.
The conventional zeroconf protocols mentioned above usually use link-local multicast packets which cannot cross boundaries between virtual local area networks (VLANs). As a result, network discovery becomes highly restrictive and is suited for small office/home office (SOHO) type of networks. Therefore, network discovery with conventional zeroconf protocols often cannot be used in an enterprise local area network deployment. For example, user devices such as an iPad on VLAN 30 will not be able to discover an AppleTV on VLAN 20.
When a router is enabled to propagate mDNS traffic between VLANs across wired and wireless networks, the wireless network is flooded with mDNS traffic that consumes valuable wireless airtime resources. Aruba AirGroup™ is a solution for wireless networks to address zeroconf networking based on mDNS protocol. By adding mDNS proxy capabilities to enterprise WLANs, mDNS messages can be forwarded across multiple subnets or VLANs. With adoption of multicast optimization algorithms, mDNS messages can be forwarded to targeted user devices based on various network policies, and thus preventing excessive multicast traffic over the WLAN.
Nevertheless, for wired networks, it isn't cost effective to adopt policy-based multicast optimization algorithms for mDNS on low cost network switches. Rather, there needs to be a light weight mechanism that can overlay virtual broadcast domains on an underlying physical network. Such mechanism shall be leveraged for any request/response based services, which is based on link-local flooding.